The present invention relates to a fluid controller to be used in fluid transport pipes requiring control of fluid, and more specifically, it relates to a fluid controller, an arrangement, piping and wiring connection of which, to semiconductor manufacturing equipment and the like, are easily achieved and do not corrode even when a corrosive fluid is used.
One of the processes used in semiconductor manufacturing is a wet etching process for etching a wafer surface using detergent water wherein a chemical solution of hydrofluoric acid or the like has been diluted with pure water. The concentration of the detergent water in this wet etching process must be controlled with high precision. Therefore, in recent years, a method for controlling the concentration of the detergent water with a flow ratio of pure water and a chemical solution has become mainstream, and a flow controller is used for controlling the flow rate of pure water or chemical solution with high precision.
Various flow controllers have been proposed conventionally, such as that shown in FIG. 7, which depicts a controller 151 of a pure water flow rate that performs fluid control when the pure water temperature is variable (see patent document 1, for example). This constitution is such that controller 151 comprises a flow rate adjustment valve 152, the aperture of which is adjusted in response to the operation of the operating pressure to adjust the pure water flow rate, an operation pressure adjustment valve 153 for adjusting the operating pressure provided by the flow rate adjustment valve 152, a flowmeter 154 for measuring the flow rate of pure water output from the flow rate adjustment valve 152, and an open/close valve 155 for allowing or blocking the flow of pure water through the flowmeter 154. By balancing operating pressure adjusted by the operation pressure adjustment valve 153 and output pressure of pure water in the flow rate adjustment valve 152, the fluid controller 151 uniformly controls the pure water flow output from the flow rate adjustment valve 152. In order that the measurement values by the flowmeter 154 are constant, there is provided a control circuit for performing feedback control of the operating pressure provided to the flow rate adjustment valve 152 from the operation pressure adjustment valve 153 based on the measurement values. Consequently, even if the output pressure in the flow rate adjustment valve 152 changes following a temperature change of the pure water, since the pure water flow rate output from the flow rate adjustment valve 152 is adjusted by adjusting in real time the operating pressure in correspondence to the change, the pure water flow rate can be maintained at a constant value with high precision.
Further, as a module for performing fluid control, there is a fluid control module 156 connected in-line with a fluid channel for transporting a fluid, as shown in FIG. 8. (For example, see patent document 2.) This constitution is such that a module comprises a housing 157 having a chemically inactive flow channel, an adjustable control valve 158 connected to the flow channel, a pressure sensor 159 connected to the flow channel, and a diaphragm section 160 positioned in the flow channel, wherein the control valve 158 and pressure sensor 159 are accommodated in the housing 157. A driver 161 having a mechanical, electrical or air-powered constitution for driving the control valve 158 and a controller 162 electrically connected to the control valve 158 and pressure sensor 159 are also accommodated in the housing 157. The effect is such that the flow rate in the flow channel is measured from the pressure difference measured in the fluid circuit and the diameter of the diaphragm section 160 and the control valve 158 is subject to feedback control and driven based on the measured flow rate, thereby deciding the flow rate in the flow channel with high precision.    Patent document 1: Laid-Open Japanese Patent Application No. H11-161342    Patent document 2: Laid-Open Japanese Patent Application No. 2001-242940
However, because a conventional pure water flow rate controller 151 is divided into many constituent elements, during installation in semiconductor manufacturing equipment, etc., pipe connections, electrical wiring or air pipe work must be performed respectively for each constituent element, resulting not only in time needed for complex tasks, but also possible errors in piping or wiring. Furthermore, other problems arise, such as pressure loss caused by connection parts when pipes are connected via tubes or joints, and this pressure loss impacts flowmeter measurements, which leads to greater measurement error, which in turn makes it difficult to control the flow rate accurately. Further, if a corrosive fluid is used, the parts in the flowmeter 154 may corrode due to infiltration by a corrosive gas.
In the conventional fluid control module 156, if a corrosive fluid is used as the fluid, the controller 162 or driver 161 will corrode when an infiltrating gas fills the fluid control module 156, affecting flowmeter measurements or functioning of the flow rate control, preventing accurate control of the flow rate or, at worst, resulting in damage. Even if the malfunction of the module is caused by corrosion of the controller 162 or driver 161, because the fluid control module 156 is designed with the various components integrated, it is difficult to repair or replace the components separately; the entire module must be replaced, resulting in higher costs in repairing damage. Further, there is the problem that if the fluid flowing into the fluid controller has a fast pulse in a pressure variable cycle, the control valve 158 operates so as to control the flow rate with respect to the pulsed fluid. However, hunting occurs and the flow rate cannot be controlled. If this state continues, the driver 161 and control valve 158 will ultimately be damaged.